Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH) networks are widely deployed in enterprise and telecommunication networks as access and backbone networks. But the inventory systems for SONET/SDH networks are typically known to be only 60 to 80 percent accurate. This means that the inventory of equipment and services in network management databases is off from the actual network state. This results in many erroneous configurations that consume network resources without serving customers or generating revenue.
FIG. 1 shows an example of a circuit fragment (e.g., a cross-connect) that was not deleted when the service was deactivated. The cross-connect 104 is associated with an add-drop multiplexer (ADM) element 102 in the SONET ring 100 shown. Since this circuit fragment does not exist in the inventory management system of the carrier, the inventory system will try to use this resource to set up new services, but all such attempts will fail. Stranded resources can also result when undocumented network elements and cards are not reflected in the inventory system. The network operator may not be aware of the availability of these resources to support new services. This results in the unnecessary deployment of additional capital and equipment. It has been estimated that the typical service provider has 20 to 30 percent stranded assets at any given time, and achieving merely five percent asset recovery would equal $15 billion in revenue savings in North America alone.
Stranded resources can also lead to longer service provisioning times because a network operator cannot determine the status and capacity of network resources in a timely fashion. In the example shown in FIG. 1, a network operator may provision a circuit using the tributary port consumed by the dangling cross-connection in the SONET network element (NE) named ADM2 as this resource is deemed “available” according to the inventory system. The operator will need to conduct time-consuming resource verification on the network element and reconcile the differences with the inventory system before the new service can be designed, provisioned and activated. It has been estimated that it takes two to three weeks to activate a service spanning multiple SONET rings in North America, and most of the time is spent on manual tasks, e.g., verifying resource availability by querying individual SONET/SDH equipment.
Current approaches tend to focus on stranded resource recovery and inventory accuracy. However, carrier networks also have a significant amount of incorrectly configured equipment that affects network reliability and performance. These configuration errors cause latent errors and are hard to detect because they are dormant until another error triggers them. For example, although an incorrectly configured 1+1 cross-connection successfully activates the service, it will fail to switch to the backup path on failure. This may result in reliability less than that promised in the service level agreement and can potentially impact revenue of the carrier.
Stranded resources and configuration errors can be caused by operator errors, prevalence of dumb devices with no management interfaces (e.g., patch panels), software bugs, and management process deficiencies, and cannot be easily prevented. The traditional solution to identifying errors is to improve the accuracy of the inventory database using an inventory reconciliation system, and then to subsequently check the updated inventory database for errors.
FIG. 2 shows a typical inventory reconciliation process 202. One first gathers up-to-date data from the SONET/SDH equipment 204 (i.e., field data) and normalizes it to some format (e.g., relational database). The field data 206 is then compared with normalized data extracted from various databases in the data reconciliation phase. This is a complex and expensive process as it works on multiple databases with different access methods and schema. A typical telecom carrier has many management systems, including a database of record (DBoR) 210 which stores the inventory data, Business Support Systems (BSS) 212 such as billing and customer care, and Operation Support Systems (OSS) 208 that manages the SONET/SDH equipment such as Element Management System (EMS) and fault management systems.
The traditional approach of using an inventory reconciliation system may require other databases, several instances of middleware to facilitate access to various management systems, a workflow management system to track work orders, and reporting software, resulting in significant investment in software and personnel. This is a long drawn out and often a very complex undertaking.
Conventional data reconciliation tools from vendors such as CoManage (Fairfax, Va.), MetaSolv (Plano, Tex.) and Granite (Telcordia of Piscataway, N.J.) typically follow the model in FIG. 2. Their main goal is to get the DBoR up-to-date and perform stranded resource recovery from the DBoR. Some tools also perform operations to reduce the amount of data that needs to be reconciled, see, e.g., CoManage TrueSource. Conventional reconciliation tools can improve the inventory system accuracy to 80 to 95 percent, but cannot eliminate all errors. This can be because the service provider network typically has many dumb devices like patch panels that are managed manually and are thus prone to human errors.
Many telecom carriers are experiencing budget constraints and are not willing to invest heavily in an inventory reconciliation system, especially on legacy SONET networks that may be replaced in a few years. These customers are looking for a low-cost approach to quickly identify stranded assets and configuration errors.
Traditional approaches to data cleanup (e.g., parsing, field standardization, matching, and consolidation) are useful for simple errors like syntax errors. However, for network recovery, there is a need to go beyond data cleanup to identify invalid configurations (which may be syntactically correct).